Light field 3D display moire simulation and suppression method

Abstract

The invention provides a light field 3D display moire simulation and suppression method. The method comprises the following steps: establishing a light field 3D display simulation model, simulating moire of a microlens array at different rotation angles, and performing frequency domain analysis to obtain an optimal rotation angle. The moire patterns generated by the micro-lens array at different rotation angles are simulated, and the high-frequency energy ratio of the moire patterns is calculated by using two-dimensional fast Fourier transform, so that the optimal rotation angle for suppressing the moire patterns is accurately obtained, and an effective solution can be provided for developing a high-definition light field 3D display screen without moire patterns.

Description

I. TECHNICAL FIELD

[0001] The present application relates to image processing technology, in particular to a moire simulation and suppression method for light field 3D display. II. BACKGROUND

[0002] Light field 3D display can display stereoscopic images without viewing glare, has the advantages of reconstructing light field distribution and full color, and is considered as one of the most promising 3D display technologies. Light field 3D display uses a microlens array as a light control element, and during display, the microlens array is located at the focal length in front of the 2D display screen to sample the micro image array. The 2D display screen is composed of red, green and blue sub-pixels arranged in a stripe pattern, and the microlens array also has a regular lens pitch. The geometric period of the sub-pixel and the period of the lens array interfere with each other to produce moire, which hinders the viewer from watching a clear 3D image. Rotating the microlens array can change the interference period and thus suppress the moire generated by the period superposition. Currently, the measurement method for moire usually uses a rotating microlens array to measure the moire at all angles. This method has measurement errors and the measurement results cannot be quantified, making it difficult to obtain the optimal rotation angle. Therefore, there is an urgent need for a moire simulation and suppression method for light field 3D display to accurately simulate and quantify the moire and find the optimal rotation angle to achieve moire suppression. III. SUMMARY

[0003] The present application provides a moire simulation and suppression method for light field 3D display, which comprises the following steps: establishing a simulation model of a light field 3D display; simulating the moire of a microlens array at different rotation angles; and obtaining an optimal rotation angle through frequency domain analysis.

[0004] Further, the step of establishing a simulation model of a light field 3D display sets the parameters of the microlens array, the parameters of the 2D display screen and the parameters of the unified coordinate system.

[0005] The step of setting the parameters of the microlens array sets the lens element pitch and the number of lens elements contained in the horizontal and vertical directions.

[0006] The step of setting the parameters of the 2D display screen sets the pixel size, the horizontal and vertical size of the sub-pixel, the horizontal and vertical interval size of the sub-pixel and the arrangement mode of the sub-pixel.

[0007] The step of setting the parameters of the unified coordinate system sets the coordinate origin, the positive direction of the x-axis and the y-axis and the hand system of the coordinate system of the microlens array and the 2D display screen.

[0008] Further, the moire simulation step of the simulation microlens array at different rotation angles, performing coordinate system rotation, calculating the position of each lens element center after the rotation of the microlens array; determining the display area corresponding to each lens element center, obtaining the color value of the display area; filling the corresponding color to the entire lens element area, simulating the sampling effect of the 2D display screen sub-pixel by the lens.

[0009] The performing coordinate system rotation, calculating the position of each lens element center after the rotation of the microlens array, the lens element center coordinates are transformed into the coordinate system after rotation through a rotation matrix.

[0010] The determining the display area corresponding to each lens element center, taking the modulus of the lens element center about the pixel size after rotation to obtain the index of the lens element center in one pixel; dividing the pixel into a sub-pixel area and an interval area, and judging the corresponding display area according to the index of the lens element center in one pixel.

[0011] The filling the corresponding color to the entire lens element area, calculating the upper and lower boundaries of the lens element after rotation, and determining the color filling area; filling the display area color corresponding to the lens element center into the entire lens element.

[0012] Iterating all lenses to obtain the moire simulation result.

[0013] Further, the frequency domain analysis step of obtaining the optimal rotation angle, obtaining the frequency spectrum information of the moire simulation result; calculating the proportion of high-frequency energy in total energy; selecting the rotation angle with the highest high-frequency energy proportion as the optimal angle.

[0014] The obtaining the frequency spectrum information of the moire simulation result, extracting the red, green and blue three-color channels of the generated moire simulation image, and performing gray scale conversion; performing two-dimensional fast Fourier transform on the gray scale image to obtain the frequency spectrum information.

[0015] The calculating the proportion of high-frequency energy in total energy, defining a high-frequency region; defining a threshold radius of the high-frequency region; calculating the distance of each point in the frequency spectrum to the frequency spectrum center to determine whether the frequency component belongs to the high-frequency region; calculating the total energy of the frequency spectrum; calculating the high-frequency energy; calculating the high-frequency energy proportion.

[0016] The selecting the rotation angle with the highest high-frequency energy proportion as the optimal angle, for each rotation angle, repeating the above steps, and selecting the rotation angle with the highest high-frequency energy proportion as the optimal angle. IV. BRIEF DESCRIPTION OF DRAWINGS

[0017] The foregoing aspects of the present application will be further clarified and readily understood in view of the following detailed description of the application, when considered in connection with the accompanying drawings and the following detailed description, in which:

[0018] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. Figure 1This is a flow chart of a method for simulating and suppressing moiré in light field 3D display according to an embodiment of the present invention.

[0019] Attachment Figure 2 FIG. 1 is a schematic diagram of a sub-pixel arrangement of a 2D display screen according to an embodiment of the present invention.

[0020] Attachment Figure 3 FIG. 1 is a spectrum diagram of moiré patterns when the rotation angle is 34 degrees according to an embodiment of the present invention.

[0021] The diagrams in the above drawings are numbered as follows:

[0022] 1 sub-pixel, 101 sub-pixel I, 102 sub-pixel II, 103 sub-pixel III, 2 sub-pixel interval.

[0023] It should be understood that the above drawings are merely schematic and not drawn to scale. V. Specific Implementation Methods

[0024] The following describes in detail a typical embodiment of a method for simulating and suppressing moiré patterns in light field 3D displays, further illustrating the present invention. It is important to note that the following embodiments are intended only to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by persons skilled in the art based on the above disclosure remain within the scope of protection of the present invention.

[0025] Attachment Figure 1 This is a flow chart of a method for simulating and suppressing moiré in a light field 3D display according to an embodiment of the present invention, comprising the following steps:

[0026] S1: Establish a light field 3D display simulation model and set the microlens array parameters, 2D display parameters, and unified coordinate system parameters. The lens element pitch of the microlens array is set to p, and the number of lens elements in the horizontal and vertical directions is set to m×n; the pixel size of the 2D display is set to R d , the horizontal and vertical sizes of sub-pixel 1 are R H and R V , the sub-pixel horizontal and vertical interval sizes are G H and G V , the sub-pixel arrangement is red, green and blue, as shown in the attached Figure 2 shown.

[0027] The upper left corner of the microlens array and the 2D display screen is set as the coordinate origin, the x-axis is to the right, the y-axis is downward as the positive direction, and the coordinate system is a right-handed system.

[0028] S2: Simulate the moiré patterns of the microlens array at different rotation angles. This step is further divided into the following three steps:

[0029] S21: Calculate the position of each lens element center after the microlens array is rotated, perform coordinate system rotation, set the rotation angle as θ, and the clockwise rotation is positive. Then, the center coordinates of the lens element in the mth row and nth column after the clockwise rotation by θ are:

[0030]

[0031] S22: Determine the display area corresponding to each lens element center. Take the remainder of the rotated lens element center with respect to the pixel size to obtain the index (x mod ,y mod ) of the lens element center in one pixel, which is represented as:

[0032]

[0033] Divide the pixel into sub-pixel areas and interval areas, determine the display area corresponding to the lens element center in which sub-pixel according to the index of the lens element center in one pixel, and represent it as:

[0034]

[0035] wherein color(m,n) represents the color of the sub-pixel corresponding to the lens element center. color(m,n) takes the value of 1 to represent the color of the sub-pixel I101 corresponding to the lens element center, 2 to represent the color of the sub-pixel II102 corresponding to the lens element center, 3 to represent the color of the sub-pixel III103 corresponding to the lens element center, and 0 to represent the interval 2 of the sub-pixel corresponding to the lens element center.

[0036] S23: Fill the corresponding color to the entire lens element area, calculate the lower bound x l(m,n) , the upper bound x t(m,n) , the lower bound y l(m,n) , and the upper bound y t(m,n) of the (m,n)th lens, and represent them as:

[0037]

[0038]

[0039] Iterate through all the lens elements to obtain the moire simulation result under the rotation angle.

[0040] S3: Obtain the optimal rotation angle through frequency domain analysis. This step is further divided into the following three steps:

[0041] S31: Obtain the frequency spectrum information of the moire simulation result. Extract the red channel I R (m,n), the green channel I G (m,n), and the blue channel I B (m,n) of the generated moire simulation image, and perform gray scale conversion:

[0042] I(m,n)=0.2989×I R (m,n)+0.5870×I G (m,n)+0.1140×I B (m,n)(6)

[0043] Where I(m,n) is the converted grayscale image. Perform a two-dimensional fast Fourier transform on the grayscale image to obtain the spectrum information, which is expressed as:

[0044]

[0045] Among them, F(u,v) is the spectrum of the grayscale image I(m,n), and the spectrum when the rotation angle θ is 34 degrees is shown in the attached figure. Figure 3 As shown, u and v are frequency domain coordinates, where u = 0, 1, ..., M-1, v = 0, 1, ..., N-1, and j is an imaginary unit.

[0046] S32: Calculate the proportion of high frequency energy to total energy. Define the high frequency region, which corresponds to the center of the spectrum (u c ,v c ) of the farther part, where (u c , v c ) is expressed as:

[0047]

[0048] Define the threshold radius R of the high-frequency area high :

[0049]

[0050] Among them, α is the proportional coefficient of the high-frequency area, and its value range is 0<α≤1.

[0051] For each point (u,v) in the spectrum, calculate its distance to the center of the spectrum (u c ,v c ) is expressed as:

[0052]

[0053] When D(u,v)≥R high , this frequency component belongs to the high frequency area.

[0054] Calculate the total energy E of the spectrum total , expressed as:

[0055]

[0056] Calculate high frequency energy E high :

[0057]

[0058] Calculate the high-frequency energy proportion P high :

[0059]

[0060] S33: Select the rotation angle with the highest high-frequency energy proportion as the optimal angle. The rotation angle θ varies from 0° to 44° in steps of 1 degree. Repeat the above steps to obtain the corresponding high-frequency energy proportions. Select the rotation angle with the highest high-frequency energy proportion as the optimal angle, at which the visibility of moiré is the smallest and the impact on image quality is the smallest.

Claims

1. A method for simulating and suppressing moiré in a light field 3D display, characterized in that: The method comprises the following steps: Establish a light field 3D display simulation model; Simulate moiré patterns of microlens array at different rotation angles; The optimal rotation angle is obtained by frequency domain analysis.

2. The method for simulating and suppressing moiré in a light field 3D display according to claim 1, wherein: The steps of establishing a light field 3D display simulation model include setting microlens array parameters, setting the lens element spacing and the number of lens elements included in the horizontal and vertical directions; setting 2D display screen parameters, setting the pixel size, sub-pixel horizontal and vertical sizes, sub-pixel horizontal and vertical spacing sizes, and sub-pixel arrangement; and setting unified coordinate system parameters, setting the coordinate origin, x-axis and y-axis positive directions, and coordinate system hand of the microlens array and 2D display screen.

3. The method for simulating and suppressing moiré in a light field 3D display according to claim 1, wherein: In the step of simulating moiré patterns of the microlens array at different rotation angles, a coordinate system is rotated to calculate the position of the center of each lens element of the microlens array after rotation; a display area corresponding to the center of each lens element is determined, and a color value of the display area is obtained; The corresponding color is filled into the entire lens element area to simulate the sampling effect of the lens on the sub-pixels of the 2D display screen.

4. The method for simulating and suppressing moiré in a light field 3D display according to claim 1 or 3, wherein: The coordinate system is rotated to calculate the position of each lens element center after the microlens array is rotated, and the coordinates of the lens element center are transformed into the rotated coordinate system through a rotation matrix; The method includes determining the display area corresponding to the center of each lens element, taking the modulus of the pixel size of the lens element center after rotation to obtain the index of the lens element center within a pixel, dividing the pixel into a sub-pixel area and an interval area, and determining the corresponding display area based on the index of the lens element center within a pixel; filling the corresponding color into the entire lens element area, calculating the upper and lower bounds of the lens element after rotation, determining the color filling area, and filling the entire lens element with the color of the display area corresponding to the lens element center; and traversing all lenses to obtain a moiré pattern simulation result.

5. The method for simulating and suppressing moiré in a light field 3D display according to claim 1, wherein: The frequency domain analysis obtains the optimal rotation angle step, obtains the spectrum information of the moiré simulation result; calculates the proportion of high-frequency energy to total energy; and selects the rotation angle with the highest proportion of high-frequency energy as the optimal angle.

6. The method for simulating and suppressing moiré in a light field 3D display according to claim 1 or 5, characterized in that: The method comprises obtaining spectrum information of the moiré simulation result, extracting the red, green and blue channels of the generated moiré simulation image, and performing grayscale conversion; performing a two-dimensional fast Fourier transform on the grayscale image to obtain spectrum information; calculating the proportion of high-frequency energy to total energy, defining a high-frequency area, defining a threshold radius of the high-frequency area, calculating the distance from each point in the spectrum to the center of the spectrum, determining whether the frequency component belongs to the high-frequency area, calculating the total energy of the spectrum, calculating the high-frequency energy, and calculating the proportion of high-frequency energy; selecting the rotation angle with the highest proportion of high-frequency energy as the optimal angle, repeating the above steps for each rotation angle, and selecting the rotation angle with the highest proportion of high-frequency energy as the optimal angle.

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